Reflection-type photoelectric switching apparatus with light-adjustable reference light detection

Abstract

A reflection-type photoelectric switching apparatus comprising a lamp for projecting light rays to an object, a photoelectric element for receiving reflected light rays from the object, a reference photoelectric element mounted on a board in side-by-side relation with the photoelectric element, a light conducting means for guiding a part of said light rays from the lamp to the reference photoelectric element, and an adjusting means for adjusting the quantity of light rays guided by the light conducting means to be balanced with that of the reflected light rays received by the photoelectric element.

What is claimed is: 
     
       1. In a reflection-type photoelectric switching apparatus having a light projecting element for projecting light rays to an object, a detection light receiving photoelectric element for receiving reflected light rays from said object, a circuit device for processing output signals from said detection light receiving element, and a housing for enclosing at least said light projecting and detection light receiving elements and circuit device, the improvement comprising a reference light receiving photoelectric element disposed adjacent to said detection light receiving element, said reference light receiving element and said detection light receiving element being reversely connected with respect to each other such that the output of one of said elements cancels the output of the other of said elements, and a reference light path including conducting means for guiding some of said light rays projected from the light projecting element to said reference light receiving element, and   means for adjusting a quantity of light rays guided by said reference light conducting means to a predetermined quantity whereby the resultant output of said reversely connected photoelectric elements can be adjusted to a desired quantity.   
     
     
       2. A reflection-type photoelectric switching apparatus according to claim 1, wherein said detection light receiving photoelectric element and said reference light receiving photoelectric element are mounted on a circuit board in side-by-side relation with respect to each other. 
     
     
       3. A reflection-type photoelectric switching apparatus according to claim 1, wherein said reference light conducting means is an optical fiber. 
     
     
       4. A reflection-type photoelectric switching apparatus according to claim 1, wherein said adjusting means includes a shading plate movable in the reference light path. 
     
     
       5. A reflection-type photoelectric switching apparatus according to claim 4, wherein said shading plate is movably connected to a screw rotatable by a knob, whereby rotation of said knob moves said shading plate in the reference light path. 
     
     
       6. A reflection-type photoelectric switching apparatus according to claim 1, wherein said adjusting means includes a knob externally disposed on said housing for easy access and adjustment.